Effects of Thymoglobulin on Human B Cells

Overview

This study is being done to better understand how immunosuppressive medications (anti-rejection medications that may or may not be approved by the Food and Drug Administration (FDA)) affect the alloimmune response (how a person's immune system reacts against another person's immune system). This will be determined by the blood tests run on the patients donated blood cells. Specifically, the investigators will test different immunosuppression medications using in-vitro assays (in the laboratory, in test tubes) alone and/or in combination to test how they can affect B-cell proliferation and differentiation, leading to an altered distribution among defined B-cell subsets and to study if exposure of B cells to thymoglobulin can have effects on subsequent interaction between B and T cell in vitro. To enable the investigators to understand how immunosuppressant medications affect immune systems in transplant patients, the investigators need to understand how they affect immune systems in healthy people. To do this, the investigators will need to study blood collected from healthy volunteers.

This is a research study of healthy subjects who will furnish blood samples for various assays over a period of one year. Peripheral blood mononuclear cells (PBMC) will be isolated from healthy volunteers and CD19+ B cells will be selected using CD19 magnetic micro-beads. B-cell cultures will be performed in culture medium consisting of Iscove's MDM (IMDM) medium (Gibco, Paisley, UK) supplemented with 10% human serum (HNS- GemCell), 0.5 ml Human Insulin (Sigma), 200mM L-Glutamine (Sigma) and 0.5% Gentamycin (Gibco). Total CD19+B cells will be cultured in the presence of anti-IgM (3μg/ml), anti-CD40 (100ng/ml), IL-21 (100ng/ml) (BCR/CD40-stimulation) for 6 days in culture plates 96 wells round bottom (1.0x105 cells/well), and Thymoglobulin at different concentrations (10 to 100 μg/ml) with or without calcineurin inhibitor (Tacrolimus, TAC) and mTOR inhibitor (Sirolimus, SRL) will be added at day 0. A variety of parameters of B cell activity including proliferation, activation, differentiation and cytokine production will be monitored by flow cytometry.These experiments are further explained in the outcome measures section below. The investigators will conduct univariate and bivariate analyses for all variables. The investigators will evaluate continuous variables using t-tests or F-tests and categorical variables using Chi-square or Fisher Exact tests. The investigators will examine data distributions and test all variables for linear relationships or non-linear relationships. Descriptive statistics (means, standard deviation, frequency) and correlations (both Pearson and Spearman) among variables will be conducted to assess the data. Necessary transformation and imputations will be conducted based on the raw data distribution. All data analyses will be performed using SAS 9.3 statistical software (SAS Inc., Cary, NC). All tests will be two-sided and an error rate of α \<0.05 will be considered statistically significant.